Originally Posted by ISTFlyer

TK might offer you different alternatives at the first stage ( in your case the offer to be rebooked on 4 Dec ). It's you who needed to push and ask an alternative rebooking on 6 Dec. I guess that you weren't satisfied with the 4 Dec proposal thus you straight went for the refund.

SHGM compensation occurs when the airline cancels your ticket or when they refuse to rebook you accordingly. In your case, it looks like you have personally requested the refund but the airline didn't force it.

Also, as I mentioned before, TK might easily find a "force majeure" excuse such as some COVID-19 restrictions and get rid of the compensation so you were out of luck for the monetary compensation, thus if you have pushed a bit, TK would have rerouted you IST-XXX-BOS presumably XXX being a US airport the same day.